1. Field of the Invention
This invention relates to a key and lock system having particular application to an automotive ignition system.
2. Description of the Related Art
Conventional vehicle anti-theft systems include mechanical keys and electronic keys. In a mechanical key system, a mechanical key is inserted into an ignition starting lock. However, unauthorized duplication of keys is common. For example, it would be very easy to duplicate keys during a stay at a vehicle work shop. Thereafter, the duplicated key could be used to steal the vehicle. In an electronic key system, a lock is unlocked when an electric signal generated by the key coincides with an electric signal generated by the lock.
U.S. Pat. No. 4,993,627 describes an electronic lock security system with a coded key. A key receiver switch has a code sensing circuit for generating signals indicative of the key's code. A decision making circuit determines if the signal received is acceptable.
U.S. Pat. No. 5,079,435 describes a vehicle anti-theft system combining a mechanical key unit with an electronic key unit. If the electronic key unit becomes unable to operate, the mechanical key unit is used for unlocking the vehicle. The mechanical key unit requires entry of coded data or insertion of a mechanical key into a key switch provided in a poorly accessible part of the vehicle body. In this system, an authorized person can operate the motor vehicle even when the electronic key unit is unable to function normally without the risk of an unauthorized person operating the vehicle. The U.S. Pat. No. 5,079,435 has the disadvantage that the use of both a mechanical and electronic unit is cumbersome.
U.S. Pat. No. 3,846,640 describes an electrical combination key lock in which a card provided with a plurality of electrical contacts is inserted into an electric contact slot. A plurality of balls form the electrical contacts of the card. Circuits of the lock are completed in the contact slot if the balls are in the correct position, thereby activating the vehicle. If the balls are in an incorrect position, a warning system is activated. The U.S. Pat. No. 3,846,640 has the disadvantage that if the key is inserted in the wrong direction the electrical contacts will not match the circuits of the lock.
Of possible general relevance to the invention are U.S. Pat. Nos.: 4,697,171; 4,151,508; and 4,980,680.
Design Patent No. 322,387 issued to the inventor of this application illustrates the shape of an electrical key.
It would be advantageous to provide a motor vehicle security system that would make it difficult to start the vehicle by using an unauthorized key or tool for providing electrical contact. It would also be advantageous to provide a key that does not require electrical signals and can be inserted in either direction into the lock.